package ljl.alg.wangzheng_camp.round1.dp;

public class _63_paths {
    
    public int uniquePathsWithObstacles2(int[][] obstacleGrid) {
        if (obstacleGrid[0][0] == 1) return 0;
        int m = obstacleGrid.length, n = obstacleGrid[0].length;
        int[][] dp = new int[m][n];
        for (int i = 0; i < m; i++) {
            if (obstacleGrid[i][0] == 1) break;
            dp[i][0] = 1;
        }
        for (int i = 0; i < n; i++) {
            if (obstacleGrid[0][i] == 1) break;
            dp[0][i] = 1;
        }
        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                if (obstacleGrid[i][j] == 0) {
                    dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
                }
            }
        }
        return dp[m - 1][n - 1];
    }
    
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        if (obstacleGrid[0][0] == 1) return 0;
        int n = obstacleGrid[0].length;
        int[] dp = new int[n];
        dp[0] = 1;
        for (int[] obstacle : obstacleGrid) {
            for (int j = 0; j < n; j++) {
                if (obstacle[j] == 1) {
                    dp[j] = 0;
                } else if (j > 0 && obstacle[j - 1] == 0) {
                    dp[j] += dp[j - 1];
                }
            }
        }
        return dp[n - 1];
    }
}
